Hello:

I have a Carrier. My system is a heat pump. In the paper it say it use two stage thermostat. Does this mean that my heat pump unit is a two stage heat pump?

I called Honeywell and the told me to select the unit as a " multistage heat pump with backup or external electric heater. I don't know is my unit have a back up or not.

Well, I installed the rth8500 and when is set to cool there is no problem at all.

While using the old digital Carrier thermostat in heat mode I noticed that for the first 3 and 1/2 minutes the ac blows air at a slow speed (is warm) then it goes very fast I can hear the strong blowing from anywhere in the house. No problem here.

Here is what is happening with the rth8500 while in heat mode. It start slow too, but after 1 minute and 20 seconds it start going very fast. It does not wait that long like the old Carrier thermostat. Could it be that the 8500 is not compatible with my unit? It is a new unit in a new house and I don't want to damage my system.

It has only six cables.

Y (yellow cable)
C (black cable)
R (red cable)
G (green cable)
W (white cable)
O (orange cable)

Honeywell CS told me connect the cables as follow:

Y - Y
C - C
R - R
G - G
W - AUX
O - O/B

One CS mention to jump AUX with E on the 8500 and another said not to do so.


I will really appreciate your help. Thank you

Nando

It start slow too, but after 1 minute and 20 seconds it start going very fast

What to slow?

Do you have a variable speed motor for the blower controlled by the circuit board?
BTW starting to slow is not a problem for the heat cycle if you have the variable speed DC drive. NOTE I do not suggest you play with any of the internal settings for that drive. The motor package is about 800.00 when you damage it.

I do not believe you have a two stage heat pump but I question why you are trying to hook this up and take a shot at causing a problem with your equipment when you do not even know what equipment you really have.

The best thing you can do is follow the directions that come with the thermostat. They are very good and you need to read through them once or twice to make sure you understand what you are doing.

From here I have no idea whet equipment you have except it is Carrier brand.

Here is a copy of your instructions for your computer file.

http://customer.honeywell.com/techlit/pdf/PackedLit/69-1902EF.pdf

Thank you for your response.

By slow I mean the speed of the air coming out.

I will read and reread the manual. Actually I did it, will try again. The only thing I will deal with is the thermostat. Nothing else.

The old thermostat manual say: "this thermostat use a green LED to indicate auxiliary heat and emergency heat operation."

Last night I saw this light on for the first time. Sorry for asking, as you may know by now I know nothing about this.

(out of curiosity) What is auxiliary heat and emergency heat operation? I goggled but did not find a clear answer.

Thank you again for taking the time to answer.


Carrier 25HBA3
Air Handler Model FV4B
Two stage Thermostat

Auxiliary heat and emergency heat operation

ARE

Basically the same thing.

Read note 5 on the first wiring diagram.

http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/25hba3-1w.pdf


Here is your inside unit

http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/im-fv4b-02.pdf

After seeing what you have which are rather deluxe units I recommend you call the people that installed your heat pump and have them install your thermostat.

One more comment.


If you are installing this thermostat thinking you will save on your utility bills you are wrong. Heat pumps are designed to run almost all the time providing a large portion of your heating needs and are VERY slow recovery after a set back for energy savings.



Usually the electric emergency/backup or accessory heat will have to come on using strait electric to recover from a heat pump set back and there goes all the energy savings you are thinking getting from the set back thermostat.

Depending upon the exact setup of your system you may also have to buy additional outdoor sensors for your new thermostat.

Sorry to be the bearer of bad news but I just tell it like it is.

I ordered the 8500 because I like much better easier to read display. Now I decided to return the 8500 and keep the one that came with the unit and not mess with it. The last thing I want is to cause any damage to a brand new unit.

One last question, does the fact that the green light came on while using the heater mean there was something wrong with the unit/compressor or it is just normal that the aux or emergency heat will kick in sometimes? And I am talking about the thermostat that came with the unit.

I was reading another post of yours where you mention: "I actually do not recommend setting back heat pump systems "

What does setting back mean?

Thank you
:)

(((One last question, does the fact that the green light came on while using the heater mean there was something wrong with the unit/compressor or it is just normal that the aux or emergency heat will kick in sometimes? And I am talking about the thermostat that came with the unit)))

Normal



A heat pump is designed to provide heat to your home on a constant level.

You can set back a heat pump(example from 72 degrees at 9:00 AM to 60 degrees during the day with a recovery set point back at 72 degrees by 6:00 PM when you come home. No problem with the set back but for the temperature to climb back to 72 degrees when you get home the strait expensive electric will probably have to run to make up the temperature loss 60 to 72 because the heat pump itself is not capable of a recover of that magnitude by itself and you will spend more energy dollars with strait electric heat than you would if you had let the heat pump run all day at 72.

I hope that made sense to you.

Smaller temp set back changes, built in intelligent glide ramps, outside sensors, and override controls can help minimumise the difference but in many cases it does not compute if you know what I mean.

The Honeywell thermostat you picked is a good one but on your system a pro needs to look at all you have now to be able to install it and add a few accessories to make it work correctly.

I completely understand the concept now. I will save more $$$ leaving the unit on " hold" at 72 all day. Setting back the unit at 62 at 6 am and then 72 at 6pm will be more expensive

I can't thank you enough for all your help answering my questions and helping me.


Thank you!

:)